A data processing device, such as a physical device or a behavioral model of a physical device, is typically tested to determine whether the device complies with a specification. One testing methodology includes placing the data processing device in a randomly determined initial state, applying a random set of stimuli to the data processing device, and comparing the resultant state to an expected state. By repeating this process with different initial states or applying different stimuli to the device, the relationship between different possible states and stimuli are tested. However, this procedure does not guarantee that the data processing device complies with the specification for cases of specific initial states and specific stimuli. Such cases can be tested by creating specific test procedures for each case, but this can be inefficient, especially for complex data processing devices. Accordingly, an improved data processing test device and methods would be useful.